Redox chemistry of copper-adenine interactions: a comprehensive cyclic voltammetric analysis of complexation and electron transfer

Understanding the interaction between biologically relevant metal ions and nucleobases is essential for advancing bioinorganic chemistry, molecular recognition, and electrochemical sensing technologies. In this study, the electrochemical behavior and coordination characteristics of a Cu(II)–adenine complex were systematically investigated using cyclic voltammetry (CV) complemented by UV-Vis, FTIR, PXRD, and EDX analyses. The novelty of this work lies in the integration of detailed electrochemical kinetic studies with comprehensive spectroscopic and structural characterization to elucidate Cu(II)–adenine complex formation and stability under varying experimental conditions. Job’s method of continuous variation revealed a stable 1:2 Cu(II) stoichiometry, while scan-rate studies confirmed a diffusion-controlled, quasi-reversible electron-transfer process. The diffusion coefficient of the complex was determined as 3.86 × 10−6 cm2 s−1, demonstrating reduced mobility relative to free Cu(II) ions and providing quantitative evidence of coordination, with a binding constant value logKf is 9.72. Variations in pH, ligand concentration, metal concentration, supporting electrolyte, and step height significantly influenced the electrochemical response, highlighting the sensitivity of the complexation process to environmental factors. Spectroscopic and diffraction analyses confirmed the formation of a new crystalline Cu(II)–adenine coordination framework involving nitrogen donor sites of adenine. These findings provide new insights into copper–nucleobase interactions and establish a foundation for future applications in bioinorganic systems, metal-based biosensors, and coordination-material design.